Abstract: A laser diode or laser diode bar mounted on a heat sink and having an insulating layer of greater thickness also mounted on the heat sink requires a lead overlying both the insulating layer and the diode to bend downward for making electrical contact. Failures have been found to occur at the bend. The provision of a pattern of slots at the bend alleviates the problem by reducing stress there. The use of such slotted leads is disclosed for diodes or diode bars individually or in a stack arrangement.

Abstract: A long wavelength infrared laser system is disclosed where radiation from laser sources such as frequency-doubled Nd:YAG or a Cr:LiSAF is used to resonantly pump a gain medium consisting of a holmium-doped fluoride crystal having a high active ion concentration. The laser pump source has a pulse duration that may be short enough to gain switch a particular transition or long enough to allow end-pumping with high energy densities without damage. The gain material has an absorption approximately resonant with the pump source wavelength, and the dopant concentration is selected to maximize absorption strength for a given excitation. The output radiation from the laser system consists of one or more wavelengths including, in particular 3.9 nm but also other infrared wavelgths such as 1.4 &mgr;m, 2.9 &mgr;m and 3.4 &mgr;m., several of which may be produced simultaneousely from the same laser material through the mechanism of cascade transitions.

Abstract: The invention relates to a diode-pumped solid-state laser (DSSL) comprises a pumping light source having a diode stack. The inventive laser also comprises a laser rod and a pumping cavity, whereby the pumping light source accommodated in a separate housing can be exchanged as a pumping module with simple handles. As a result, the pumping light source is protected from electrostatic discharge of the diodes, mechanical stress and from contamination. Given that it is possible to accommodate alternative pumping light sources of varying pumping capacities in the pumping module, the user can exchange the pumping module when the pumping module is worn as well as when additional power is required.

Abstract: A generator for producing a low-noise, high-frequency signal has a monomode first laser connected via an optical isolator to a second laser so as to permit light generated by the fist laser to be injected into the second laser. The difference in the frequencies of the lasers and the intensity of the injected light is selected so as to prevent the second laser from locking onto the free-running frequency of the first laser.

Abstract: The semiconductor laser device of the present invention includes a GaAs substrate and a multi-layer structure formed on the GaAs substrate. The multi-layer structure includes an active layer for emitting light. The active layer includes an InNxAsyP1−x−y (where 0<x<1 and 0≦y<1) layer that is lattice-matched with the GaAs substrate.

Abstract: An optically pumped vertical-cavity surface-emitting laser (VCSEL) device and a method of fabricating the device utilize two separate substrates that perform a filtering operation to selectively transmit only light having a long peak wavelength that is generated by the device. The optically pumped VCSEL device is a self-pumped device that can generate the pump light to drive the device to emit output laser light having a long peak wavelength. The optically pumped VCSEL device includes a short-wavelength VCSEL formed on one of the two substrates and a long-wavelength VCSEL formed on the other substrate. The short-wavelength VCSEL is a current-driven VCSEL that generates short-wavelength light to drive (i.e., optically pump) the long-wavelength VCSEL. The short-wavelength VCSEL and the long-wavelength VCSEL are bonded together such that the two substrates are separated by the two VCSELs.

Abstract: Laser diode pumped mid-IR wavelength sources include at least one high power, near-IR wavelength, injection and/or sources wherein one or both of such sources may be tunable providing a pump wave output beam to a quasi-phase matched (QPM) nonlinear frequency mixing (NFM) device. The NFM device may be a difference frequency mixing (DFM) device or an optical parametric oscillation (OPO) device. Wavelength tuning of at least one of the sources advantageously provides the ability for optimizing pump or injection wavelengths to match the QPM properties of the NFM device enabling a broad range of mid-IR wavelength selectivity. Also, pump powers are gain enhanced by the addition of a rare earth amplifier or oscillator, or a Raman/Brillouin amplifier or oscillator between the high power source and the NFM device. Further, polarization conversion using Raman or Brillouin wavelength shifting is provided to optimize frequency conversion efficiency in the NFM device.

Abstract: Individually addressable laser crystals are optically coupled to a single slab of an optical carrier that transmits substantially without distortion. The crystals are separate for thermomechanical isolation but may be closely spaced (generally on the order of 0.003 inch apart), and may originate as a single crystal cut into separate segments.

Abstract: A laser with a quasi-top-hat pump beam has a modified intensity profile that produces a parabolic temperature gradient. The laser includes a high reflector and an output coupler defining a laser cavity. A gain medium positioned in the laser cavity. A first diode pump source produces a first pump source beam. An intensity profile of the first diode pump source beam is tailored to produce the parabolic temperature gradient across the gain medium.

Abstract: A microlaser is provided that has a microresonator and a pump source for side pumping the microresonator. The microresonator includes an active gain medium and a Q-switch that extend lengthwise between the opposed end faces of the microresonator. The pump source is therefore positioned so as to introduce pump signals into the microresonator via the side surface that is adjacent to and defined by the active gain medium. By side pumping the microresonator, the microlaser can generate a series of pulses having greater pulse energies and greater average power levels than the pulses provided by conventional microlasers. In addition, the side pumped microlaser can also generate pulses having greater pulse widths than the pulses provided by conventional microlasers of a similar size.

Abstract: A diode array (32) which includes a diode bar (22) having a plurality of laser diodes (42) within an active region (40) so as to emit light parallel to an optical axis (26), generally parallel to the laser diodes (42). The diode bars (22) are sandwiched between a pair of spacer layers (34, 36). Each spacer layer (34, 36) includes two or more spacers (48, 50). The spacers (48, 50) in each layer (34, 36) are configured such that gaps (52, 54) between contiguous spacers (48, 50) are at a non-parallel angle (&THgr;) relative to the optical axis (26) of the diode bar (22). By orienting the gaps (52, 54) between the spacers (48, 50) at non-parallel angle relative to the optical axis (26) of the laser diodes (40), the gaps (52, 54) span several laser diodes (40), thus averaging any inhomogeneous effects caused by the gaps (52, 54) resulting in a relatively more uniform output from the various laser diodes (40) forming the diode bar (22).

Abstract: A laser diode array comprises a plurality of substantially parallel spaced metal plates, each plate having a laser diode mounted upon one side of the plate. The plates are supported electrically insulated from one another on mounting means. The diodes, connected electrically in series, when energized illuminate an oblong workpiece area disposed a certain distance opposite the array. In a preferred embodiment, the mounting means comprises flexible rod means passing through respective apertures of the plates, thus enabling the array to assume a curved configuration, thereby enabling the array to illuminate a straight as well as a curved oblong workpiece area.

Abstract: The average power capability of a solid-state laser is increased by cooling the lasing element to a cryogenic temperature. The laser pump chamber is configured to define a flow path for circulating cryogenic fluid. The cryogenic cooling is achieved for rod, slab, active-mirror or disc amplifier-type lasing elements.

Abstract: A laser diode bar mounting structure includes a dielectric substrate with an overlying conductor, and diode bar spaces through the conductor layer to support laser diode bars within them. The bar spaces are configured with parallel upper sidewalls and flared out or expanded bottoms to dissipate capillary action of solder under the diode bars.

Abstract: Abstract of the Disclosure A solid-state laser apparatus has a solid-state laser medium inside a resonator. A pump light source such as a semiconductor laser apparatus generates pump light, and an optical system focuses the pump light on the solid-stated laser medium such that its distribution is not only inside but also at least in part outside the resonator mode in the solid-state laser medium, say, over more than 50% of the total length of the solid-state laser medium.

Abstract: A high power, diode pumped laser has a Nd:YVO4 gain media. Scaling to higher powers is achieved with the use of a low doped gain media, increasing the length of the gain media as well as increasing the pump volume. Passive cooling is extended to output powers of 10 W or greater .

Abstract: A laser assembly including a silicon base and method are provided for assembling lasers on a platform in a reliable, low cost process that is suitable for high volume production. The platform can be a monolithic silicon base which has high thermal conductivity, a low coefficient of thermal expansion, and whose features can be formed with close tolerances in a low cost, reliable manner. Materials with similar coefficients of thermal expansion are used in order to maintain alignment during unexpected heating and cooling. Furthermore, a method is described that substantially eliminates the need for adhesives to bond laser components to a platform. The resultant laser can be very robust, stable, and can provide reliable operation over extended time periods.

Abstract: A method and apparatus for fabricating extremely robust opto-electronic devices on a monolithic support structure is provided. Incorporated into the support structure are registration structures that are used to quickly and accurately align the various components associated with the device, typically eliminating the need for manual component alignment. The registration structures are fabricated using conventional lithographic techniques, offering alignment accuracy of a micrometer or less. Utilizing the registration structures, a gain module is fabricated that is comprised of at least a pump laser, an optical element, and a solid state gain medium. The pump laser is preferably a semiconductor diode laser that pumps the edge of the gain medium, thus eliminating many of the difficulties that arise from end pumping the medium.

Abstract: An optical amplifier pumping system with built-in redundant reliability for lightwave communication system provides plural levels of redundancy. A first level of redundancy deals with redundancy in the form of plural primary laser diode sources in the lightwave communication system. A second level of redundancy deals with redundancy of multiple single mode laser emitters on the same chip or bar sufficiently segmented so as not to interfere with operation of or cause failure to adjacent or neighboring emitters on the same chip or bar. A third level of redundancy deals with redundancy of a plurality of fiber pump sources for pumping a plurality of serially connected injection signal fiber amplifiers.

Abstract: A method of reducing the amount of unwanted radiation emitted from a semiconductor laser device involves coating a transparent portion the device intended to transmit radiation with a partially reflective layer.

Abstract: A laser marking system comprises a high power fiber laser consisting of a double clad fiber having a doped core surrounded by an inner pump cladding and providing an optical output for marking; a high power laser diode source for pumping the double clad fiber laser via an input into the inner pump cladding; an optical scanner coupled to receive the marking output from the double clad fiber laser to scan the output over a surface of an article to be marked by sweeping the marking output in one, two or three dimensions to form strokes, the completion of which comprises indicia to be marked the article surface; and a controller to control the operation of the scanner in synchronism with the modulation of the laser diode pump source to initiate the marking output and sweep and modulate the marking optical output in one, two or three dimensions to form strokes comprising the indicia. A main advantage of the fiber laser marking system over CO.sub.

Abstract: A solid-state laser includes a high-absorption coefficient solid-state gain medium such as Nd:YVO.sub.4 that is side pumped with a semiconductor laser diode array. The resonant cavity of the solid-state laser is positioned so that the TEM.sub.00 mode is spaced from the face of the laser through which the laser is pumped by a distance sufficient to reduce diffraction losses but sufficiently near to allow coupling of pump light into the gain mode. The gain medium, the doping level of the gain medium, and the operating temperature of the pump laser are selected to efficiently couple pump light into the gain mode. The pump laser is positioned to side pump the gain medium without collimating or focusing optics between the pump laser and the face of the gain medium. A gap between the pump laser and the gain medium is empirically selected to match the angular extent of the pump laser output light to the height of the gain mode at the position of the gain mode fixed to optimize coupling and diffraction losses.

Abstract: In a method and an apparatus for driving a diode-pumped solid-state laser, the light power emitted by the solid-state laser (1) is determined as a measurement signal, using a measurement apparatus. By comparison of the measurement signal with a predetermined light power target value, a control deviation is determined in a control amplifier the deviation being converted in a generator into a driver current for a laser diode used as a pump diode for the resonator of the solid-state laser. For the damping of high-frequency disturbances of the light power, in a high-bandwidth negative feedback branch the high-frequency components of the measurement signal are filtered out by means of a high-pass filter and are supplied to a fast control amplifier. In a control element connected in parallel to the laser diode, a portion of the driver current supplied to the laser diode is controlled dependent on the high-frequency components of the measurement signal.

Abstract: The invention relates to an optical array for symmetrization of the beam of multiple sequentially fixed adjacent laser diodes, their respective output radiation being asymmetrical in relation to a first and a second direction that are perpendicular to each other. A cylindrical lens with sufficient isoplanacy is mounted on the tilted optical axis (z axis), which is perpendicular to the plane predetermined by the two directions (x, y). The lens collimates and displaces the output beam bundle of the individual laser diodes in the first direction (x). The cylindrical lens is mounted downstream a directional element that deflects the beam bundle of the individual laser diodes in the second direction (y) with different deflecting angles respectively in such a way that the centers of gravity of the individual beam bundles converge at a predetermined spacing.

Abstract: A light amplification device comprises a laser slab and optics for establishing an optical beam at the lasing wavelength. The beam travels inside the slab in a zig-zag path between two reflecting faces. The slab is also cooled through the reflecting faces. The slab is pumped through one or more pumping faces, each pumping face being distinct from the reflecting faces. Light from the pump is incident upon the slab in a direction that is transverse to the plane of propagation of the lasing wavelength beam. This arrangement separates the cooling interfaces from the pumping interfaces. Distortions in the beam due to thermal effects are largely averaged out by the zig-zag path. The device may function as either a laser or an optical amplifier.

Abstract: One facet of each of a set of N semiconductor laser chips is provided with an antireflection coating through which the chip emission is coupled, via a wavelength multiplexer, with a partially reflecting Bragg reflector providing an N-way wavelength multiplexed laser output for pumping an optical amplifier. The wavelength multiplexer may be constituted by a cascade arrangement of Mach-Zehnders.

Abstract: A solid laser crystal added with Pr.sup.3+ is pumped by a InGaN laser diode to generated a laser beam. A fiber having a core added with Pr.sup.3+ is pumped by a GaN laser diode to generated a laser beam. A fiber having a core added with Pr.sub.3+ is pumped by a GaN laser diode to generate fluorescence and incident light in the wavelength range of the fluorescence is amplified by energy of the fluorescence.

Abstract: A laser amplification system with a lasant solid-state material is pumped by pumped light sources and in the case of which one or several pumped beams are guided by mirrors or other optical aids such that each individual pumped beam is focussed several times on different points of the solid-state material, the latter being present in the form of a cohesive or separate solid body which is designed such that the pumped beam is absorbed only in the focal regions, whereby the latter are optically pumped, and in that the laser beam is deflected and guided such that it irradiates all these focal points and is amplified in this manner. This provides a laser amplification system in which the system characteristics are optimized simultaneously, which, in addition, permits a compact construction and is designed such that it is suitable for mass production at reasonable cost.

Abstract: A semiconductor device such as a light emitting semiconductor device comprising a mask layer having opening areas and a selective growing layer comprising a semiconductor grown selectively by way of the mask layer, with each of the mask layer and the selective growing layer being disposed by two or more layers alternately. The semiconductor device is manufactured by a step of laminating on a substrate a mask layer having opening areas and a selective growing layer comprising a semiconductor grown selectively way of a mask layer, each by two or more layers alternately and a subsequent step of laminating semiconductor layers thereon. Threading dislocations in the underlying layer are interrupted by the first mask layer and the second mask layer and do not propagate to the semiconductor layer. The density of the threading dislocations is lowered over the entire surface and the layer thickness can be reduced.

Abstract: A semiconductor laser light source includes: a semiconductor laser array which emits laser beams whose polarization planes are parallel to each other and whose divergent angles .theta.z and .theta.x in two orthogonal directions satisfy an inequality .theta.z>.theta.x; a cylindrical lens which converges the laser beams emitted from the semiconductor laser array in a direction that decreases the divergent angle .theta.z; a wave plate which controls the direction of polarization so that the polarization planes of the laser beams having passed through the cylindrical lens are at 90 degrees to each other; a birefringent optical element which merges by the birefringent effect the optical paths of the laser beams having passed through the wave plate; and a light emitting surface which converges the laser beams merged by the birefringent optical element in a direction that decreases the divergent angle .theta.x.

Abstract: We have found that the conversion efficiency of a Er/Yb-doped cladding pumped fiber amplifier increases with increasing signal input power. Thus, preamplification of the input signal by means of an Er-doped fiber amplifier can result in increased conversion efficiency of the cladding pumped power amplifier. Such increased efficiency is desirable, lessening heat removal problems and/or facilitating increased reliability.

Abstract: Laser device with semiconducting diodes. The invention concerns a device with semiconducting laser diodes comprising individual wafers (8), made of a good heat-conducting material, assembled parallel to one another with semiconducting diode connector bars (9) placed between them as braces, said connector bars only taking up a longitudinal portion of the spaces between the wafers, in which they are located, and the longitudinal portions (17) of said spaces between the wafers, not taken up by said semiconducting connector bars, being used as flow channels for a cooling fluid.

Abstract: A transverse pumping system for a laser rod uses orthogonally arranged banks of laser diodes which create overlapping patterns of illumination inside the rod.

Abstract: A system and method for reducing wavefront distortion in high-gain diode-pumped laser media by providing a non-uniform current profile to be delivered to a pumping array comprised of laser diodes distributed on a laser medium. A signal processor provides for partitioning an electric current emitted from a diode driver such that the pumping array receives a non-uniform current profile resulting in a controlled thermal gradient near the periphery of the laser substrate. By controlling this thermal gradient at the region where an exit laser beam leaves the laser medium, the thermally-induced exit beam distortion is minimized.

Abstract: An assembly of N laser diode arrays. Each diode is fitted to the end of a base which forms the anode and is traversed by a hole. The holes of all the bases define a channel for the circulation of fluid for cooling the assembly of diode arrays. Each module includes an array, a base and a corresponding cathode. The modules are separated from each other by a flat joint or gasket.

Abstract: A method and apparatus pump a laser gain medium of a laser rod having a first longitudinal axis. At least one pump light source emits pump light to the laser rod, and the pump light source has a second longitudinal axis which is perpendicular to the first longitudinal axis. Radiation from various laser diode arrays is collimated and uniquely arranged in a vertical orientation in relation to the laser gain medium. Reflectors focus the collimated radiation from the diode arrays onto the laser gain medium to achieve fundamental mode operation or Transverse Electromagnetic mode (TEM00 mode) operation. Both laser gain medium and reflectors may be simultaneously cooled with appropriate fluids in the apparatus. The assembly of the apparatus may be extended to hold a plurality of vertically oriented laser diode arrays to increase the laser pump power.

Abstract: Stable operation of an ultra-compact modelocked fiber laser generating short optical pulses generally without use of any non-fiber, intra-cavity polarization-manipulating elements is obtained by employing a saturable absorber coupled to one end of a highly-birefringent fiber serving as the laser cavity. Once the laser is modelocked in one of the polarization axes of the highly-birefringent fiber, the degeneracy of the polarization axis is eliminated and cw oscillation along the other polarization axis is also prevented. Without a polarization-dependent loss in the cavity, the modelocked polarization axis is indeterminate, i.e., modelocking can occur on either of the polarization axes. However, the introduction of only a small polarization dependent loss is sufficient to ensure the reliable start-up of modelocking on only the low-loss axis.

Abstract: A solid state laser, comprising (a) a resonator, (b) at least one laser diode array for side pumping said resonator, and (c) at least one fan-out-covering optical system, between said resonator and said at least one laser diode array, does not suffer from thermal problems and provides a high quality beam. The solid state laser may be air cooled.

Abstract: A multi-cavity, solid-state laser system for producing a plurality of output laser beams includes a plurality of optical energy sources, a solid-state laser medium, and resonating means associated with each of said plurality of optical energy sources. The plurality of optical energy sources produces input optical energy and each is spaced from an adjacent one of the plurality of optical energy sources by a predetermined distance. The input optical energy is produced substantially along a line and is received by the solid-state laser medium. The laser medium has first and second side surfaces that substantially oppose each other and first and second end surfaces that also substantially oppose each other. The input optical energy enters the laser medium through its first side surface and it is substantially absorbed in the laser medium so as to produce a high-gain region associated with each of the plurality of optical energy sources.

Abstract: A light amplifier device comprises an amplifier medium plate consisting of an upper part comprising two lateral faces (11) and (12) and a lower part comprising two lateral faces (13) and (14), the lateral faces (11) and (13) being located on a first face of the amplifier medium, the lateral faces (12) and (14) being located on a second face of the amplifier medium opposite said first face, at least two light beams (2) and (2') amplified by the amplifier medium and optical pumping means of said amplifier medium, wherein the light beam (2) is introduced into the amplifier medium at a lateral face (11) or (12) and the light beam (2') is introduced into the amplifier medium at a lateral face (13) or (14). The faces (11) and (12) are antiparallel to each other, the faces (13) and (14) being also antiparallel to each other. Application to power lasers.

Abstract: In a laser-diode-pumped solid state laser, a solid laser crystal is pumped by a pumping laser beam emitted from a laser diode and a harmonic of light emitted from the pumped solid laser crystal is caused to make laser oscillation by a resonator structure containing therein a nonlinear optical crystal. The electric current to be poured into the laser diode is controlled so that the pumping laser beam emitted from the laser diode is kept at an output level at which the pumping laser beam cannot cause the harmonic of light emitted from the solid laser crystal to make laser oscillation though pumping the solid laser crystal.

Abstract: A laser marking system and an associated microlaser apparatus are provided which include a submount, a plurality of pump sources operably mounted upon the submount, and a microlaser disposed in alignment with the pump sources such that pump signals emitted by the pump sources pump respective portions of the active gain medium of the microlaser to produce a laser output. In order to impart a mark upon a workpiece that has a number of pixels, the laser marking system can be configured such that each pixel of the resulting mark is produced by the laser output generated by a different portion of the active gain medium of the microlaser in response to pumping by a respective one of the pump sources.

Abstract: A laser pump cavity apparatus with integral concentrator provides uniform gain and high absorption efficiency. The apparatus has a doped solid-state laser medium, a concentrator which has a top cladding layer formed on the top surface of the doped laser medium having a cylindrical focusing surface, a bottom cladding layer formed on the bottom surface of the doped laser crystal having a cylindrical focusing surface, and edge cladding layers formed on the side surfaces of the doped laser medium. Cold plates, each of which also preferably has one cylindrical surface of substantially identical shape, are placed in thermal contact with the cylindrical focusing surfaces of the top and bottom cladding layers to absorb heat. The cylindrical focusing surfaces preferably have hyperbolic or quasi-hyperbolic shape. The laser pump cavity apparatus is preferably edge-pumped with several laser diode arrays focused toward the line foci of the cylindrical focusing surfaces in directions transverse to a laser beam axis.

Abstract: A laser-diode-pumped solid state laser in which a solid state laser crystal is pumped by a light beam produced by a laser diode and which is not lower than 10 W in the internal power of the resonator includes a temperature control circuit which keeps the inside temperature of a resonator at a predetermined temperature and, a wavelength selector which is disposed in the resonator and selects one of a plurality of oscillation modes in the resonator, thereby making the laser oscillate in a single mode. The wavelength selector has characteristics such that the increase in temperature of the wavelength selector due to absorption of a laser beam is smaller than a value such that when the temperature of the wavelength selector changes by the value or more, the oscillation mode selected by the wavelength selector changes.

Abstract: An optical semiconductor device has a structure in which a semiconductor active layer is sandwiched by a p-type semiconductor cladding layer and an n-type semiconductor cladding layer and a p-type contact layer is formed on the p-type semiconductor cladding layer side and an n-type contact layer is formed on the n-type semiconductor cladding layer side, wherein two ferromagnetic layers are formed on the n-type contact layer and two ferromagnetic layers are formed on the p-type contact layer. Magnetization directions of a pair of ferromagnetic layers vertically opposed to each other are set to be parallel to each other, and the magnetization directions of adjacent ferromagnetic layers are inverted to each other.

Abstract: Apparatus for stabilizing multiple laser sources having distinguishable optical characteristics, e.g., in polarization field or operational wavelength, comprises a plurality of semiconductor laser sources having respective lasing cavities capable of lasing within a narrow bandwidth of wavelengths and providing spectral outputs at their respective laser exit facets having different optical characteristics from one another. The spectral output beams of the sources may be coupled to respective optical fibers and the beams combined via a beam combiner, e.g., a polarizing beam combiner or a WDM combiner. The beam combiner combines the beam outputs forming a single beam which is launched into an output optical fiber. At least one feedback fiber grating is provided in at least one of the optical fibers with the number thereof depending upon distinguishable optical characteristics of the multiple laser sources.

Abstract: A semiconductor excitation solid-state laser apparatus, in which a cross-sectional area of an optical guide plate leading an excited beam emitted from a semiconductor laser element to a solid-state laser medium is made larger in the side of the semiconductor laser element thereof, while a cross-sectional area thereof is made smaller in the side of the solid-state laser medium.

Abstract: In accordance with the present invention, a wavelength selectable laser source comprises a tunable pump source, an array of waveguide lasers for emitting light at respectively different wavelengths and a router for directing light from the pump source to an appropriate waveguide laser. A second router can be used to direct all laser outputs to a common output waveguide. The result is a wavelength selectable, stable signal source. In preferred embodiments the routers are dense wavelength-division multiplexers (DWDMs) and the waveguide lasers are rare-earth doped fiber lasers. Alternative embodiments provide a variety of ways of routing the pumping source.

Abstract: A microchip laser is formed from at least one portion of laser material and at least one nonlinear crystal. The laser material and nonlinear crystal are in physical contact with each other and an angled surface of either the laser material or the nonlinear crystal forms an air-spaced etalon between the laser material and the nonlinear crystal. The axis of the microchip laser passes through the etalon formed between the laser material and the nonlinear crystal. The etalon in the laser cavity produces a single mode output. Additionally, the nonlinear crystal within the cavity may operate, in conjunction with a polarization dependent gain cross-section in the laser material, as a birefringent filter to reduce the bandwidth of laser emission from a broadband active laser material.

Abstract: A laser system which generates short duration pulses, such as under five nanoseconds at an energy level of up to a few milli-Joules per pulse (mJ/p) with near diffraction limited beam quality. A laser crystal is pumped (excited) by diode lasers. A resonator having at least two mirror surfaces defines a beam path passing through the laser crystal. The beam path in the resonator is periodically blocked by a first optical shutter permitting pump energy to build up in the laser crystal, except for a short period near the end of each pumping period. While the first optical shutter is open a second optical shutter blocks the light in the resonator except for periodic short intervals, the intervals being spaced such that at least one light pulse traveling at the speed of light in the resonator is able to make a plurality of transits through the resonator, increasing in intensity by extracting energy from the excited laser crystal on each transit.